The present invention relates to systems to periodically attentuate an electrical signal in response to changes in selected conditions. Signal attenuation means are utilized in numerous applications from highly sophisticated applications such as computers to more straightforward applications in simple electrical or electromechanical devices.
Signal attenuation can, of course, be accomplished manually by observation of the situation to be controlled and manual manipulation of the signal control means. In the alternative, attenuation is accomplished by sensing devices responsive to the condition to be controlled and use of devices to automatically attenuate signals to controllers affecting the condition to be controlled.
In one application of the foregoing, specifically in electronic circuitry, attenuation can be accomplished by the use of amplifier means for the controlled or a controller signal with continuous feedback and gain adjustment of the amplifier circuit. Such arrangements provide satisfactory control in some instances but in other applications, for example in attenuation of the output of multiple input sound actuated sound amplification systems, such arrangements have been less satisfactory than desired. Also, such systems are subject to distortion resulting from transient and feedback effects.
Other attenuation methods have provided for stepwise, rather than continuous attenuation. Such arrangements have generally been manually controlled and where automatic control has been provided as disclosed in an article entitled "Automatic Attenuator Rapidly Changes Signal Level", Electronics, Sept. 15, 1969 at page 120 have utilized continuous monitor of incoming signals to shift attenuation levels. Such systems have been found less than desirable in sound amplification because the rapid switching of output channels leads to undesirable interference with the quality of transmitted program material.
Additionally, no attenuation device is known which can be utilized to attenuate an output signal in response to a large number of input signals where the state of the input signals is summed and changes in attenuation are effected in response to the change in the sum rather than in response to the change in individual inputs.